This section outlines the drivers and modern approaches to minimization of waste material and maximization of efficiencies in the processing of red and white meat. Process optimization and good housekeeping practice have been highlighted, and approaches to overall minimization of end waste material and effluent have also been addressed. Enhancements in processing efficiency and minimization of waste can lead to a range of positive benefits for the meat processor, including: a reduction in manufacturing costs and resultant increase in profitability; cost savings on raw materials and energy; reduced environmental pollution; reduced waste disposal and treatment costs; improved worker health and safety; diminished need for 'end-of-pipe' solutions; and an enhanced image for the company and industry.
While meat cuts represent the most significant primary product from an abattoir, by- and co-products such as hides, bone, blood, fat and offal are also generated via the animal slaughtering process. The profitability of an abattoir can often depend on the extent to which these materials are minimized and/or utilized in a value-added manner. For example, edible co-products are further processed into saleable products, and inedible byproducts are converted into animal feeds or feed supplements, often through the rendering process. Utilization of, and value addition to, meat processing wastes are covered in later sections of this chapter.
As with most food processing operations, the key waste and efficiency issues associated with abattoir operations include: (1) the high consumption of clean potable water; (2) the generation of high-strength/biochemical oxygen demand (BOD) effluent streams and by-/co-products; and (3) the consumption of energy. For some locations, odour and noise may also be problematic. Techniques for minimizing waste and maximizing operational efficiency include improved housekeeping practices by staff, process optimization, application of new technology and/or new product design. Indeed, through effective application of these techniques aimed at reducing inefficient use of resources and avoiding unnecessary generation of waste, the processor can benefit from reduced operating costs, reduced waste treatment/disposal costs and reduced liability.
In the abattoir setting, large quantities of water are used for the watering and washing of livestock, washing of transport infrastructure (e.g. trucks), washing of carcasses and by-/co-products, and cleaning and sterilizing equipment and processing areas. Strategies for reducing water consumption can involve technical solutions or equipment upgrades. However, revision of operator practice and cleaning procedures can lead to some of the most significant gains in efficiency and waste reduction. Suggested approaches are summarized in Table 13.1.
Most water consumed at abattoirs ultimately becomes effluent. Abattoir effluent contains high levels of organic matter due to the presence of manure, blood, fat and other animal remains. The effluent can also contain high levels of sodium, phosphates and nitrates. The most significant contributors to the organic load include blood and fat-containing material, and blood represents the major contributor to the nitrogen content of the effluent stream. High contents of sodium and phosphorus can also be present in effluent, and these usually originate from manure and stomach contents. At those plants where rendering of animal remains occurs, the effluent typically represents the single most significant source of pollutant load from the abattoir. Usual strategies for reducing the pollutant load of abattoir effluent focus on excluding blood, fat, manure and animal remains from the
Table 13.1 Suggested approaches to minimization of waste and maximization of efficiency in modern meat processing operations
Area of operation Suggested approaches to operational efficiency
Dry cleaning prior to final wash/rinse with water. High-pressure/low-volume systems. Automatically operated equipment and shut-off valves. Dry dumping techniques.
Reuse of 'grey' and cooling water for some non-critical cleaning operations (e.g. washing livestock).
Segregate organic material from the slaughtering operation.
Collect solid material (by-/co-products) for waste value addition.
Install screens to eliminate solid material from drains. Limit fat in water effluent through use of low-pressure washing of carcass.
Segregate high-BOD streams from others and manage them separately.
Implement 'switch-off' programmes and install power-down/off equipment where appropriate. Enhance insulation on heating/cooling systems. Recover waste heat from various unit processing steps. Install more-energy-efficient equipment. Implement a preventative maintenance programme to ensure maximum efficiency of equipment at all times. Eliminate leak points for hot water and steam.
effluent stream. Implementation of such a strategy means isolating materials from the effluent stream before they enter drains and using alternatives, where available, to wet cleaning methods. Approaches to the minimization of effluent are summarized in Table 13.1.
In an abattoir, thermal energy is used to heat water for cleaning, scalding for hair removal, rendering, blood coagulation and blood drying. Approximately 80% of total energy consumed by abattoirs is provided by thermal energy from the combustion of fuels in on-site boilers, and the remaining 20% is usually provided by electricity - used for operating equipment in the slaughter and boning areas, for by-/co-product processing, for refrigeration and for compressed air. Typical ranges for energy consumption are 1200-4800 MJ/tonne of hot standard carcass weight. The consumption of energy is an area where considerable savings can be made almost immediately with no capital investment, through simple housekeeping approaches. Additional savings can be made through the use of more-energy-efficient equipment and heat recovery systems, although these require capital investment. Approaches to maximization of energy savings are summarized in Table 13.1.
In summary, waste can be minimized and processing efficiency maximized in a modern abattoir and meat processing operation through a number of worker and process/product improvements. These include (1) housekeeping improvements to work practices and proper equipment maintenance (typically low cost); (2) optimizing existing processes/equipment to reduce resource consumption (typically low/medium cost); (3) adapting and adopting new technologies to reduce resource consumption and minimize waste via enhanced operating efficiencies (typically capital intensive but often with short payback time); and (4) changing product design to reduce waste disposal/treatment, reduce energy consumption and enhance efficiency of production (typically long-term, but often with large paybacks).
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